Body fat mass distribution and interrupter resistance, fractional exhaled nitric oxide, and asthma at school-age

Background: Obesity and asthma often coexist. We hypothesized that detailed body fat distribution measures might be more strongly associated than body mass index (BMI) with childhood asthma. Objective: We examined the associations of total body and abdominal fat measures with respiratory resistance (Rint), fractional exhaled nitric oxide (FENO), and risks of wheezing and asthma in school-aged children. Methods: In a population-based prospective cohort study among 6178 children aged 6 years, we measured BMI, fat mass index, android/gynoid ratio, and preperitoneal and subcutaneous fat mass by physical examinations, dual-energy x-ray absorptiometry, and ultrasound, respectively. We performed Rint and FENO measurements, and assessed physician-diagnosed wheezing and asthma by questionnaires. Results: A higher BMI was associated with a higher Rint (Z score [95% CI], 0.06 [0.01-0.12]) and increased risk of wheezing (odds ratio [95% CI], 1.07 [1.00-1.14], per Z score BMI increase), but not with FENO or asthma. A high fat mass index was associated with a higher Rint (Z score [95% CI], 0.40 [0.13-0.68]). A high android/gynoid fat mass ratio was associated with a lower FENO(Sym% [95% CI], -9.8 [-16.3 to -3.4]), whereas a high preperitoneal fat mass was associated with a higher FENO (Sym% [95% CI], 6.5 [0.1-12.9]). Subcutaneous fat mass was not associated with any respiratory outcome. Conclusions: Studying detailed body fat distribution measures might provide better insight into the obesity-asthma paradigm.